Abstract—Recently an issue of global warming as a result of increase in CO₂ released to the atmosphere rise an awareness to the possibility of reduction in worldwide agricultural production. Cassava (Manihot esculenta L. Crantz) and sweet potato (Ipomoea batatas (L.) Lam.) are known as important daily food for Indonesian people. We investigated short term (14 days) growth responses of cassava and sweet potato to elevated CO₂ concentrations. The plants were five months old prior to exposure to elevated CO₂ concentration of 612 ppm, 777 ppm and 959 ppm, and 357 ppm (ambient CO₂ concentration). Exposure of CO₂ was conducted in a transparent plastic growth chamber for 14 days. After the exposure to elevated CO₂ concentrations of 612 and 777 ppm, cassava plants showed reduction in plant height, but at 959 ppm there was a significant increase. There was also an increase in chlorophyll content, HCN and proline concentration in cassava especially at 959 ppm. Sweet potato plants also showed significant increase in plant length at 959 ppm, whereas at 612 and 777 ppm showed reduction. There was also an increase in chlorophyll content of sweet potato leaves after the treatment. It can be concluded that high Elevated CO₂ concentration at 959 ppm seems to increase short term growth of cassava plants and sweet potato plants, whereas at 612 and 777 ppm plants reduced their growth.